1. Field of the Invention
The present invention relates in general to computer equipment and, more particularly, to an apparatus and method of providing communication between RAID controllers in computer storage systems.
2. Description of the Prior Art
Computer storage systems typically include one or more high-capacity disk arrays for storing digital information. Commonly, the disk arrays are arranged in a redundant array of independent disks (RAID) topology. The RAID topology provides stability, security and redundancy as to the computer storage system. A disk system with RAID capability can protect its data and provide on-line, immediate access to its data, despite a single (some RAID storage systems can withstand two concurrent disk failures) disk failure. RAID capability also allows for the use of a number of less expensive disks while providing increased storage capacity. A common RAID topology includes the use of one or more RAID controllers, which serve to channel data flow to a particular disk in the array while coordinating data transfer across the entire array among other functions.
In computer storage systems, the need for built-in redundancy is very desirable. As a result, a computer storage system with RAID capability can include two or more RAID controllers, or initiators. If a first RAID controller fails for any reason, then a second RAID controller can be employed to take on the first controller's functions, a process which is commonly known in the industry as “fail over”, and “fail back” when function to the first RAID controller is restored.
In an example dual redundant RAID controller storage system, communication is required between the first and second RAID controllers. The communication between RAID controllers ensures redundancy in the event of a failover. This communication can be accomplished by a variety of low-level interfaces, such as PCI, I2C or Ethernet. In some computer systems, however, a generic high-speed fabric connects computing components. For example, the high-speed fabric can connect a RAID controller with a set of storage devices. The low-level communication between RAID controllers is typically not performed over the high speed fabric. An additional connection, such as the installation of an external cable between RAID controllers, must be made. The requirement of an additional connection between RAID controllers adds extra complexity in the design process and cost in the manufacturing process.
Thus, a need exists for an apparatus and method of communication between individual RAID controllers in a multi-controller RAID or similar topology mass storage system of an overall computer system.